From fbrennan@berkeley.edu Sat Aug 05 07:29:34 1995 Path: ashpoly!cascade!brgate!saturno!berkeley!fbrennan From: fbrennan@berkeley.edu (Fiona Brennan) Newsgroups: comp.dsp Subject: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Aug05.072934.8739@berkeley.edu> Date: Sat, 05 Aug 1995 07:29:34 GMT Organization: UC Berkeley Department of EECS NNTP-Posting-Host: berkeley.edu X-Newsreader: WinVN 0.99.5 Lines: 11 Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. However, when downsampling from 44.1 kHz to 64 Hz, accumulator overflow in the biquad IIR filter can destabilize the loop. Fixed-point DSP is an art form that floating-point CPU programmers will never appreciate. -- Fiona Brennan *PLONK* filter active for trolls. Amiga 3000T - NetBSD 1.0 From krodriguez@hanse.de Sun Aug 06 00:06:34 1995 Path: ashpoly!bigsur!pacrim!jpgate!kamome!hanse!krodriguez From: krodriguez@hanse.de (Katrin Rodríguez) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Aug06.000634.3179@hanse.de> Date: Sun, 06 Aug 1995 00:06:34 GMT References: <1995Aug05.072934.8739@berkeley.edu> Organization: Hanse-Netzwerk Hamburg NNTP-Posting-Host: hanse.de X-Newsreader: NewsWatcher 2.0b24 Lines: 9 In article <1995Aug05.072934.8739@berkeley.edu>, fbrennan@berkeley.edu (Fiona Brennan) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. -- Katrin Rodríguez Opinions expressed are solely my own and not those of Hanse-Netzwerk Hamburg. ------------------------------------------------------------ From mokonkwo@clari.net Mon Aug 07 06:49:34 1995 Path: ashpoly!cascade!transat!eunet-fr!teletel!clari!mokonkwo From: mokonkwo@clari.net (Mathieu Okonkwo) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Aug07.064934.4195@clari.net> Date: Mon, 07 Aug 1995 06:49:34 GMT References: <1995Aug05.072934.8739@berkeley.edu> <1995Aug06.000634.3179@hanse.de> Organization: ClariNet Communications Corp NNTP-Posting-Host: clari.net X-Newsreader: NewsWatcher 2.0b24 Lines: 11 In article <1995Aug06.000634.3179@hanse.de>, krodriguez@hanse.de (Katrin Rodríguez) writes: > Beautiful assembly code! The 24-bit word size of the 56001 is tailor-made for high-precision audio filtering. Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. Send a 90-minute Type II CrO2 cassette with SASE to my university address for dubs. -- Mathieu Okonkwo | mokonkwo@clari.net PGP Key fingerprint: 659C C4FB 6DCB 49E6 "Keep the channels open." From mnakamura@delphi.com Tue Aug 08 12:46:34 1995 Path: ashpoly!cascade!transat!eunet-de!hansebox!delphi!mnakamura From: mnakamura@delphi.com (Mateo Nakamura) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Aug08.124634.4946@delphi.com> Date: Tue, 08 Aug 1995 12:46:34 GMT References: <1995Aug05.072934.8739@berkeley.edu> Organization: Delphi Internet Services NNTP-Posting-Host: delphi.com X-Newsreader: WinVN 0.99.5 Lines: 10 In article <1995Aug05.072934.8739@berkeley.edu>, fbrennan@berkeley.edu (Fiona Brennan) writes: > Why fixed-point integer math requires careful scaling when tracking a 14.2 Hz carrier. > This leaves over 95% of the DSP56001's 16.5 MIPS available for other audio tasks. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. -- Mateo Nakamura Opinions expressed are solely my own and not those of Delphi Internet Services. ------------------------------------------------------------ From arodriguez@uu.net Thu Aug 10 05:31:34 1995 Path: ashpoly!cascade!bigsur!uu!arodriguez From: arodriguez@uu.net (Andrei Rodríguez) Newsgroups: comp.dsp Subject: Re: Discussion: Fixed-point Q15 arithmetic on Motorola DSP56001 vs IEEE floating point Message-ID: <1995Aug10.053134.7998@uu.net> Date: Thu, 10 Aug 1995 05:31:34 GMT References: <1995Aug05.072934.8739@berkeley.edu> <1995Aug06.000634.3179@hanse.de> <1995Aug07.064934.4195@clari.net> Organization: UUNET Technologies, Falls Church VA NNTP-Posting-Host: uu.net X-Newsreader: Netscape 1.1N Lines: 12 In article <1995Aug07.064934.4195@clari.net>, mokonkwo@clari.net (Mathieu Okonkwo) writes: > Real programmers write in C, not arcane DSP microcode. With Pentium chips hitting 100 MHz, dedicated DSPs are obsolete. > Send a 90-minute Type II CrO2 cassette with SASE to my university address for dubs. Ran your code on my NeXTstation Turbo. It locked onto the carrier within 1.2 seconds of vinyl lead-in. Unsubscribe me from this list! (Wait, this is Usenet, never mind). -- Andrei Rodríguez | arodriguez@uu.net PGP Key fingerprint: 1D40 B4C9 10D4 6750 "Keep the channels open."